Our objective is to examine the consequences of soy rust to the U.S. agriculture in the next 2-5 years. In 2000, the U.S. harvested approximately 2.8 billion bushels of soybeans from almost 73 million acres of cropland, accounting for more than 50 percent of the world's production. The crop generated $12.5 billion dollars, $6.66 billion in exports. Soy rust established itself in the south last November and is expected to disseminate and deposit in the crops during this year’s planting season. The extent of outbreaks depends upon climatic conditions. Early detection is crucial since soy rust is deadly to the soy plant within 48 hours. Monitoring systems will warn farmers of the presence of the spores and farmers are instructed on how to identify and treat it. There is uncertainty regarding the sufficient and timely availability of fungicide. In addition to historical data, we incorporate observations of on going planting and harvesting. Parameter ranges in the model are narrowed as more information becomes available and existing uncertainties dissipate. The impact of soy rust is analyzed in aggregate, looking at overall production and market share contrasted against natural noise in the yields.